1. Field of the Invention
The invention is directed in general to remote control systems including transmitters and/or receivers which operate on a coded signal and, in particular, to a universal remote control transmitter that can acquire the transmission frequency and modulation pattern of another transmitter without a prior knowledge of these parameters.
2. Background of the Invention
Transmitter-receiver controller systems are widely used for remote control and/or actuation of devices or appliances such as garage door openers, gate openers, security systems, and the like. For example, most conventional garage door opener systems use a transmitter-receiver combination to selectively activate the drive source (i.e., motor) for opening or closing the door. The receiver is usually mounted adjacent to the motor and receives a coded signal (typically radio frequency) from the transmitter. The transmitter is typically carried in the vehicle by a user and selectively activated by the user to open or close the garage door.
Different manufacturers of such transmitter-receiver systems generally utilize different transmission protocols or patterns for transmitting the coded signal. They typically operate the transmitter-receiver systems at different transmission frequencies within the allocated frequency range for a particular type of system. The modulation pattern typically includes two aspects: 1) a device code (equivalent to a device address) for the transmitter and receiver, and 2) a transmission format, i.e., the characteristics of the transmitted signal including timing parameters and modulation characteristics related to encoded data. The transmission pattern used by one manufacturer is usually incompatible with that provided by other manufacturers.
Currently available transmitter-receiver systems typically employ custom encoders and decoders to implement the transmission pattern. These encoders and decoders are fabricated with custom integrated circuits such as application-specific integrated circuits (ASICs). They are fixed hardware devices and allow very limited flexibility in the encoding/decoding operation or in the modification of the encoding/decoding operation.
Thus, in such existing transmitter-receiver systems, it is necessary to know the transmission frequency accepted by the receiver and to match or determine the modulation pattern recognized by the receiver. In a number of transmitter-receiver systems, the modulation pattern is determined by setting a plurality of dual inline (DIP) switches (or a modulation pattern selection circuit) on the transmitter and by similarly setting a plurality of DIP switches (or a corresponding modulation pattern selection circuit) on the receiver. Once the required frequency and the modulation pattern are defined, a compatible transmitter can be provided to operate with the receiver. The DIP switches or the modulation pattern selection circuit may also be manually reset to match the modulation pattern of signals transmitted by a new transmitter to that of the existing receiver. Alternatively, both the existing receiver and new transmitter can be reprogrammed with a new modulation pattern. However, existing reprogramming techniques require prior knowledge of the transmission frequency and modulation protocol of the existing transmitter. In addition, they can only be implemented in compatible transmitters and receivers using complex circuits.
Accordingly, there is a need in the technology for an apparatus and method of providing a transmitter that can acquire the transmission frequency and modulation pattern of another transmitter/receiver system, without a prior knowledge of either of the parameters, and without manual selection of either of the parameters. There is also a need to provide a transmitter that is operable within a wide frequency spectrum and is compatible with any modulation scheme.
A method and apparatus for providing a universal transmitter that can detect and emulate a transmission signal of a transmitter, the transmission signal having a corresponding transmission frequency and a corresponding modulation pattern. The universal transmitter comprises: a detection circuit that detects a frequency and a modulation pattern of a transmitted signal of a separate transmitter and a memory. A processor coupled to the detection circuit and the memory, stores a frequency value representative of the detected frequency and a plurality of value representative of the detected modulation pattern, in the memory. A transmitting circuit coupled to the processor, is operable to transmit an output signal having the frequency and the modulation pattern of the transmission signal.